The invention relates to an electrically operated valve construction, for closed-loop control of fluid flow through the valve.
Past constructions of the character indicated reflect the entrenched view that electrical-control circuitry for a valve which is to govern fluid flow, particularly liquids, should, to the greatest extent possible, be kept safely remote from the valve and the fluid it accommodates. Such thinking necessarily means much wiring and wiring connections, all invitations to electrical (and therefore to valve) malfunction. And in cases where an array of such valves is to function concurrently, each with its own sensed regulation of its own flow condition, the wiring and connection problem becomes particularly acute.
An example of such problems in an array of valves is to be found in the production of high-quality metal sheet which, after rolling, must be cooled without curl, prior to coiling for storage and shipment to achieve the flatness needed for avoidance of curl an array of like coolant-spray valves is connected to a coolant-supply manifold which spans the width of moving hot sheet material as it issues from the rolling mill, and each valve spray serves a different increment of width of the hot moving sheet. Since cooling effectiveness is different for the different increments of width, and since the distribution of coolant flow as a function of width-increment location is essential to avoidance of curl, a separate sensing of the transverse profile of sheet-temperature conditions is continuously necessary, at a location downstream from that of coolant-spraying; and each valve must be automatically controlled to correctly reflect its local increment of cooperative influence upon the observed profile, to the end that the observed profile will remain as predetermined for satisfactory production without curl. To externally bring all electrical wiring to and from the valves, and to and from the profile-sensing apparatus, is necessarily to require great electrical complexity.